Cells

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Cells
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II. Composite Cell

• Cell Membrane (Plasma Membrane)
• 1. Separates cell from its external environment
• 2. Gives cell its shape
• 3. Site of many metabolic reactions
• 4. Selectively permeable

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II. Composite Cell

• B. Cell Membrane Structure
• 1. Phospholipid bilayer
• a. inside is hydrophobic (fatty acids)
• b. outside is hydrophilic (phosphate
• group)
• c. oxygen, carbon dioxide pass
• through easily
• d. amino acids, sugars, proteins,
• nucleic acids, and various ions have
• a hard time passing through.
• 2. Other Lipids(steroids)- cholesterol
  stabilizes, increases insolubility to water.

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II. Composite Cell

• 3. Proteins
• a. Rodlike receptor proteins span the membrane
  and aid in communication.
• b. Globular proteins may form pores or
  selective channels for certain molecules or ions.
• c. Carbohydrates bound to proteins(glycoprotein
  s) enable cells to recognize one another.

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II. Composite Cell

• C. Cytoplasm (cytosol)
• 1. Jelly-like material inside the cell
• 2. Is in constant motion (Cytoplasmic Streaming)
• 3. Surrounds organelles

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II. Composite Cell

• D. Cell Structures
• 1. Endoplasmic Reticulum(ER)
• a. Membrane system of folded
• sacs and tunnels.
• b. Rough ER (ribosomes)
• produces and transports proteins
• c. Smooth ER synthesizes lipids,
• absorbs fat, metabolizes drugs
• 2. Ribosomes
• a. Most numerous organelle
• b. Provide the work site, and
• enzymes for making proteins.

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II. Composite Cell

• 3. Golgi Apparatus
• a. Stack of membranes
• b. Processes and modifies
• proteins from the ER.
• c. Packages the modified
• protein.
• d. Secretes the protein
• outside the cell.
• 4. Mitochondria
• a. Respiration centers of the cell.
• b. Release energy from
• nutrients taken into the cell.
• c. Find in cells that need a lot of
• energy.

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II. Composite Cell

• 5. Lysosomes
• a. Small, round organelles that
• contain digestive enzymes.
• b. Mainly in animal and fungal
• cells.
• c. Digests tissue (breasts after
• weaning, uterus after
• childbirth, inactive muscle)
• 6. Peroxisomes
• a. Membranous sacs
• b. Contains catalytic enzymes
• (breakdown toxins)
• c. Abundant in liver and
• kidney

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II. Composite Cell

• 7. Microtubules and Microfilaments
• a. Shape and support
• cell (cytoskeleton)
• b. Move cellular material.
• 8. Centrosome
• a. Two hollow cylinders at
• right angles to one another.
• b. Help distribute
• chromosomes to newly
• forming cells.

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II. Composite Cell

• 9. Cilia and Flagella
• a. Cilia Short, hairlike
• structures
• b. Flagella Whiplike
• structures
• 10. Vesicles (vacuoles) Membrane enclosed sacs

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II. Composite Cell

• 10. Nucleus (site where nucleic acids are
  synthesized)
• a. Nuclear Envelope
• b. Chromatin Fine strands of
• DNA and protein(histones)
• c. Chromosome A strand of
• chromatin that coils up when a cell is
  dividing
• d. Nucleolus Site where
• ribosomes are synthesized and
• assembled.